Set execution policy to Bypass when creating the initial runspace

This eliminates the need to have `SetExecutionPolicy` which is a slow function
that first queries a bunch of policies and then within PowerShell itself (as in,
using a cmdlet) sets it to `Bypass`. However, we just want the process scope
(AKA runspace scope) to have the execution policy set to `Bypass` all the time
so that we can import our bundled modules, such as PSReadLine.

Author: andyleejordan

src/PowerShellEditorServices/Services/PowerShellContext/PowerShellContextService.cs

@@ -11,6 +11,7 @@
 using System.Management.Automation.Remoting;
 using System.Management.Automation.Runspaces;
 using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -281,6 +282,15 @@ public static Runspace CreateRunspace(PSHost psHost, PSLanguageMode languageMode
             // should have the same LanguageMode of whatever is set by the system.
             initialSessionState.LanguageMode = languageMode;
 
+            // We set the process scope's execution policy (which is really the runspace's scope) to
+            // Bypass so we can import our bundled modules. This is equivalent in scope to the CLI
+            // argument `-Bypass`, which (for instance) the extension passes. Thus we emulate this
+            // behavior for consistency such that unit tests can pass in a similar environment.
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                initialSessionState.ExecutionPolicy = ExecutionPolicy.Bypass;
+            }
+
             Runspace runspace = RunspaceFactory.CreateRunspace(psHost, initialSessionState);
 
             // Windows PowerShell must be hosted in STA mode

test/PowerShellEditorServices.Test/PowerShellContextFactory.cs

@@ -46,6 +46,8 @@ public static PowerShellContextService Create(ILogger logger)
                 TestProfilePaths,
                 new List<string>(),
                 new List<string>(),
+                // TODO: We want to replace this property with an entire initial session state,
+                // which would then also control the process-scoped execution policy.
                 PSLanguageMode.FullLanguage,
                 null,
                 0,

test/PowerShellEditorServices.Test/Session/PowerShellContextTests.cs

@@ -147,10 +147,9 @@ await this.powerShellContext.ExecuteCommandAsync<string>(
         }
 
         [Trait("Category", "PSReadLine")]
-        [SkippableFact]
+        [Fact]
         public void CanGetPSReadLineProxy()
         {
-            Skip.If(IsWindows, "This test doesn't work on Windows for some reason.");
             Assert.True(PSReadLinePromptContext.TryGetPSReadLineProxy(
                 NullLogger.Instance,
                 PowerShellContextFactory.initialRunspace,